This invention relates to apparatus for testing the release torque of container caps and, more particularly, to container cap torque testers having improved apparatus therein for testing for and identifying improperly capped containers.
Container cap torque testers are commonly used in connection with commercial container filling lines wherein plastic, glass or metal containers are filled with liquids or powders and then automatically capped by machinery which clamps the containers at a work station and rotates threaded container caps onto the containers at the work station.
Variations in the torque with which the caps are tightened onto the containers occur during the capping process for a number of reasons, including changes in manufacturing tolerances for the threaded container caps and containers, variations in pneumatic line pressures and electrical voltages employed in the machinery used in the container capping operation, wear on the container clamping and/or cap grasping members employed therein, and changes in ambient temperature and humidity during the container capping operation.
The variations in the torque with which the caps are tightened onto the containers results in the subsequent arising of potentially significant problems in connection with the handling and/or usage of the capped containers. For example, containers having insufficiently torqued container caps are subject to leakage during packing and shipping, and containers having caps which are excessively torqued present problems for the ultimate consumer when he or she attempts to remove the container cap to use the product therein.
Heretofore, torque testers have been employed to check the torque level at which container caps have been applied to containers. One example of conventional torque testing apparatus comprises a hand held, manually-operated torque tester which is utilized to selectively sample the release torques of a small percentage of the capped containers that are produced by a container filling and capping line. Its use involves applying sufficient torque to the container cap to break the seal between the cap and its container in order to obtain the release torque reading. Accordingly, the container cap is opened relative to the container and this form of torque testing apparatus thus employs destructive testing of each of the selected containers, and a time consuming, manual operation, as well. Moreover, the accuracy of such hand held manually-operated torque testers is limited due to the fact that variations in readings are obtainable based on user-controlled functions such as, for example, the speed with which the user applies de-capping torque to the container cap, alignment between the container cap and the torque applying instrument, ambient conditions, and the like.
More recently, the operation of container cap torque testers has been mechanized to eliminate some of the problems associated with the earlier, manual forms of torque testers. One example of such a mechanized torque tester is shown in U.S. Pat. No. 4,696,144 to Geza E. Bankuty and LeRoy F. Byron, which is assigned to the assignee of the present application. In U.S. Pat. No. 4,696,144 an automated torque tester is disclosed which is capable of being installed in a container filling and capping line so that it can provide continuous, non-destructive torque testing with respect to the entire production of filled and capped containers produced by the line. Although the torque tester exemplified by the foregoing patent represents a significant improvement over the earlier, manual torque testers, which employed selective sampling and destructive testing of the samples selected, the accuracy of the later torque tester, while greatly improved over that of the manual earlier versions of torque testers, is still less than optimum due to the fact that a cumbersome cap grasping and torque applying mechanism is employed therein which introduces errors (as much as 2 inch-pounds) and spikes (which may be seen on an oscilloscope) into the torque readings.
It is, therefore, a primary object of this invention to provide improved apparatus for testing the release torque of container caps.
Another object of this invention is to provide improved apparatus for testing for a predetermined minimum release torque of container caps at a torque testing station.
A still further object of this invention is to provide improved apparatus for non-destructively testing that the release torque of container caps at a torque testing station in said apparatus is above a predetermined minimum value, and for rejecting those containers that do not pass such tests.
Yet another object of this invention is to provide improved automatic apparatus for testing for a predetermined minimum release torque of container caps, which apparatus further includes selectively operable means for destructively testing selected ones of the containers, on a sampling basis, to determine the actual release torque of the container caps thereon.
Further objects and advantages of this invention will become apparent as the following description proceeds.